U.S. patent number 9,330,650 [Application Number 13/821,738] was granted by the patent office on 2016-05-03 for sound masking device and sound masking method.
This patent grant is currently assigned to YAMAHA CORPORATION. The grantee listed for this patent is Toshiaki Ishibashi, Eiko Kobayashi. Invention is credited to Toshiaki Ishibashi, Eiko Kobayashi.
United States Patent |
9,330,650 |
Kobayashi , et al. |
May 3, 2016 |
Sound masking device and sound masking method
Abstract
A sound masking device includes: a sound pick-up unit which
picks up a sound, and which produces a picked-up sound signal based
on the sound, a masking sound signal producing unit which produces
a masking sound signal from the picked-up sound signal a sound
emitting unit which emits a masking sound based on the masking
sound signal, and an echo cancelling unit which performs an echo
cancelling process on the picked-up sound signal by performing an
adaptive filtering process on the masking sound signal, and by
subtracting the filtered masking sound signal from the picked-up
sound signal. The masking sound signal producing unit produces a
masking sound signal having a level corresponding to an amplitude
level of the picked-up sound signal which has subjected to the echo
cancelling process.
Inventors: |
Kobayashi; Eiko (Hamamatsu,
JP), Ishibashi; Toshiaki (Fukuroi, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Kobayashi; Eiko
Ishibashi; Toshiaki |
Hamamatsu
Fukuroi |
N/A
N/A |
JP
JP |
|
|
Assignee: |
YAMAHA CORPORATION
(Hamamatsu-shi, JP)
|
Family
ID: |
45810761 |
Appl.
No.: |
13/821,738 |
Filed: |
September 8, 2011 |
PCT
Filed: |
September 08, 2011 |
PCT No.: |
PCT/JP2011/070497 |
371(c)(1),(2),(4) Date: |
March 08, 2013 |
PCT
Pub. No.: |
WO2012/033165 |
PCT
Pub. Date: |
March 15, 2012 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20130163772 A1 |
Jun 27, 2013 |
|
Foreign Application Priority Data
|
|
|
|
|
Sep 8, 2010 [JP] |
|
|
2010-200468 |
Mar 16, 2011 [JP] |
|
|
2011-057384 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04R
3/02 (20130101); G10K 11/002 (20130101); G10K
11/1754 (20200501); H04K 3/825 (20130101); H04K
3/43 (20130101); H04M 9/082 (20130101); H04K
3/45 (20130101); H04K 2203/12 (20130101); H04K
3/42 (20130101) |
Current International
Class: |
G10K
11/00 (20060101); H04M 9/08 (20060101); H04R
3/02 (20060101); H04K 3/00 (20060101); G10K
11/175 (20060101) |
Field of
Search: |
;381/71.1-71.14 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
05-022391 |
|
Jan 1993 |
|
JP |
|
2005-084645 |
|
Mar 2005 |
|
JP |
|
2006-217542 |
|
Aug 2006 |
|
JP |
|
2006-261967 |
|
Sep 2006 |
|
JP |
|
2007-235864 |
|
Sep 2007 |
|
JP |
|
2009-118062 |
|
May 2009 |
|
JP |
|
Other References
International Searching Authority Report and International Search
Report for PCT/JP2011/070497. Dated Sep. 8, 2010. cited by
applicant .
Notification of Reason for Refusal issued in Japanese Patent
Application No. 2011-057384 issued on Aug. 26, 2014, English
translation provided. cited by applicant .
Chinese Office Action cited in Chinese counterpart application No.
CN201180043378.4, dated Feb. 28, 2014. English translation
provided. cited by applicant.
|
Primary Examiner: Al Aubaidi; Rasha
Attorney, Agent or Firm: Rossi, Kimms & McDowell LLP
Claims
The invention claimed is:
1. A sound masking device comprising: a sound pick-up unit
configured to pick up a sound, and produce a picked-up sound signal
based on the sound; a masking sound signal producing unit
configured to produce a masking sound signal from the picked-up
sound signal, the masking sound signal causing the sound picked up
by the sound pick-up unit to be hardly hearable by a third person;
a sound emitting unit configured to emit a masking sound based on
the masking sound signal; and an echo cancelling unit configured to
perform an echo cancelling process on the picked-up sound signal by
performing an adaptive filtering process on the masking sound
signal and by subtracting the filtered masking sound signal from
the picked-up sound signal, wherein the produced masking sound
signal has a level corresponding to an amplitude level of the
picked-up sound signal that has been subjected to the echo
cancelling process.
2. The sound masking device according to claim 1, further
comprising: a transmission characteristic detecting unit configured
to acquire transmission characteristics to be used in the filtering
process in the echo cancelling unit, and output frequency
characteristics of the transmission characteristics, and wherein
the produced masking sound signal has a frequency feature provided
in the frequency characteristics of the transmission
characteristics.
3. The sound masking device according to claim 2, wherein: the
masking sound signal producing unit outputs an adjustment content
of the masking sound signal based on the frequency characteristics
of the transmission characteristics, to the echo cancelling unit,
and the echo cancelling unit uses the adjustment content to
estimate the transmission characteristics to be used in the
filtering process.
4. The sound masking device according to claim 3, further
comprising: a sudden-sound detecting unit configured to detect a
sudden sound contained in the picked-up sound signal that has
subjected to the echo cancelling process, the sudden sound
consisting of a characteristic sound in which a sound generation
time is shorter than a reference threshold, and wherein upon the
sudden-sound detecting unit detecting the sudden sound, the masking
sound signal producing unit produces the masking sound signal, at a
timing outside a period including the sudden sound.
5. The sound masking device according to claim 2, further
comprising: a sudden-sound detecting unit configured to detect a
sudden sound contained in the picked-up sound signal that has
subjected to the echo cancelling process, the sudden sound
consisting of a characteristic sound in which a sound generation
time is shorter than a reference threshold, and wherein upon the
sudden-sound detecting unit detecting the sudden sound, the masking
sound signal producing unit produces the masking sound signal, at a
timing outside a period including the sudden sound.
6. The sound masking device according to claim 1, further
comprising: a sudden-sound detecting unit configured to detect a
sudden sound contained in the picked-up sound signal that has been
subjected to the echo cancelling process, the sudden sound
consisting of a characteristic sound in which a sound generation
time is shorter than a reference threshold, and wherein upon the
sudden-sound detecting unit detecting the sudden sound, the masking
sound signal producing unit produces the masking sound signal, at a
timing outside a period including the sudden sound.
7. A method of masking sound using a sound masking device
comprising: a sound pick-up unit configured to pick up a sound, and
produce a picked-up sound signal based on the sound; a masking
sound signal producing unit configured to produce a masking sound
signal from the picked-up sound signal, the masking sound signal
causing the sound picked up by the sound pick-up unit to be hardly
hearable by a third person; a sound emitting unit configured to
emit a masking sound based on the masking sound signal; and an echo
cancelling unit configured to perform an echo cancelling process on
the picked-up sound signal by performing an adaptive filtering
process on the masking sound signal and by subtracting the filtered
masking sound signal from the picked-up sound signal, wherein the
method comprises: a sound pick-up step of picking up the sound and
producing a picked-up sound signal based on the sound using the
sound pick-up unit; a masking sound signal producing step of
producing the masking sound signal from the picked-up sound signal
using the masking sound signal producing unit; a masking sound
outputting step of outputting the masking sound based on the
masking sound signal using the sound emitting unit; and an echo
cancelling step of performing the echo cancelling process on the
picked-up sound signal using the echo cancelling unit, wherein the
produced masking sound has a level corresponding to an amplitude
level of the picked-up sound signal that has been subjected to the
echo cancelling process.
8. The sound masking method according to claim 7, further
comprising: a transmission characteristic detecting step of
acquiring transmission characteristics to be used in the filtering
process in the echo cancelling step, and outputting frequency
characteristics of the transmission characteristics, and wherein
the produced masking sound signal has a frequency feature provided
in the frequency characteristics of the transmission
characteristics.
9. The sound masking method according to claim 8, wherein: the
masking sound signal producing step outputs an adjustment content
of the masking sound signal based on the frequency characteristics
of the transmission characteristics, and the echo cancelling step
uses the adjustment content to estimate the transmission
characteristics to be used in the filtering process.
10. The sound masking method according to claim 8, further
comprising: a sudden-sound detecting unit configured to detect a
sudden sound contained in the picked-up sound signal that has
subjected to the echo cancelling process, the sudden sound
consisting of a characteristic sound in which a sound generation
time is shorter than a reference threshold, and wherein upon the
sudden-sound detecting unit detecting the sudden sound, the masking
sound signal producing unit produces the masking sound signal, at a
timing outside a period including the sudden sound.
11. The sound masking method according to claim 9, further
comprising: a sudden-sound detecting step of detecting a sudden
sound contained in the picked-up sound signal that has subjected to
the echo cancelling process, the sudden sound consisting of a
characteristic sound in which a sound generation time is shorter
than a reference threshold; and wherein upon the sudden-sound
detecting step detecting the sudden sound, the masking sound signal
producing step produces the masking sound signal, at a timing
outside a period including the sudden sound.
12. The sound masking method according to claim 7, further
comprising: a sudden-sound detecting step of detecting a sudden
sound contained in the picked-up sound signal that has been
subjected to the echo cancelling process, the sudden sound
consisting of a characteristic sound in which a sound generation
time is shorter than a reference threshold, wherein upon the
sudden-sound detecting step detecting the sudden sound, the masking
sound signal producing step produces the masking sound signal, at a
timing outside a period including the sudden sound.
13. A sound masking device comprising: a receiving unit configured
to receive a picked-up sound signal; a masking sound signal
producing unit configured to produce a masking sound signal from
the picked-up sound signal, the masking sound signal causing a
sound from which the picked-up sound signal originates, to be
hardly hearable by a third person; an outputting unit configured to
which output the masking sound signal; and an echo cancelling unit
configured to perform an echo cancelling process on the picked-up
sound signal by performing an adaptive filtering process on the
masking sound signal and by subtracting the filtered masking sound
signal from the picked-up sound signal, wherein the produced
masking sound signal has a level corresponding to an amplitude
level of the picked-up sound signal that has been subjected to the
echo cancelling process.
Description
This application is a U. S. National Phase Application of PCT
International Application PCT/JP2011/070497 filed on Sep. 8, 2011,
which is based on and claims priority from JP 2010-200468 filed on
Sep. 8, 2010, and JP 2011-057384 filed on Mar. 16, 2011, the
contents of which is incorporated in its entirety by reference.
TECHNICAL FIELD
The present invention relates to a sound masking device which
produces a masking sound for making a voice uttered by a specific
person to be hardly heard by another person in the periphery, and
also to a sound masking method.
BACKGROUND ART
Conventionally, various devices for producing a masking sound based
on an input sound to make the sound from which the input sound
originates, difficult to be hardly heard, such as a sound masking
device have been proposed. In the device of Patent Document 1, for
example, an environmental sound is input to a sound inputting
section, and an environmental sound signal indicating the waveform
of the environmental sound is analyzed. Based on a result of the
analysis, the device of Patent Document 1 produces a specific
generated sound signal. In this case, the device of Patent Document
1 produces the generated sound signal so that a person hears the
environmental sound and a generated sound output from the device as
a mixed sound (sound which is not uncomfortable) of a specific
mode.
PRIOR ART REFERENCE
Patent Document
Patent Document 1: JP-A-2009-118062
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
In the device disclosed in Patent Document 1, if the device is not
placed in an infinite open space, the generated sound feedbacks to
the sound inputting section, and the input sound contains an echo
of the generated sound. In the case where such a device is used in
a sound masking process, therefore, an echo of the masking sound is
input together with the voice of a specific person to the sound
inputting section. In a conventional device, consequently, a mixed
sound of the voice of a specific person with an echo sound is
subjected to a waveform analysis, and hence there is a case where a
masking sound cannot be produced based only on the voice of the
specific person.
It is an object of the invention to provide a sound masking device
and sound masking method which can produce a masking sound while
suppressing an influence of a sound other than a sound to be
masked.
Means for Solving the Problems
The sound masking device which can solve the problem includes: a
sound pick-up unit configured to picks up a sound, and produce a
picked-up sound signal based on the sound; a masking sound signal
producing unit configured to produce a masking sound signal from
the picked-up sound signal, the masking sound signal causing the
sound picked up by the sound pick-up unit to be hardly hearable by
a third person; a sound emitting unit configured to emit a masking
sound based on the masking sound signal; and an echo cancelling
unit configured to perform an echo cancelling process on the
picked-up sound signal by performing an adaptive filtering process
on the masking sound signal and by subtracting the filtered masking
sound signal from the picked-up sound signal, and in the masking
sound signal producing unit, a masking sound signal having a level
corresponding to an amplitude level of the picked-up sound signal
which has subjected to the echo cancelling process is produced.
Preferably, the sound masking device further includes a
transmission characteristic detecting unit configured to acquire
transmission characteristics to be used in the filtering process in
the echo cancelling unit, and which outputs frequency
characteristics of the transmission characteristics, and the
masking sound signal producing unit produces the masking sound
signal having a frequency feature provided in the frequency
characteristics of the transmission characteristics.
Preferably, the masking sound signal producing unit outputs an
adjustment content of the masking sound signal which is based on
the frequency characteristics of the transmission characteristics,
to the echo cancelling unit, and the echo cancelling unit uses the
adjustment content in estimation of the transmission
characteristics to be used in the filtering process.
Preferably, the sound masking device further includes a
sudden-sound detecting unit configured to detect a sudden sound
contained in the picked-up sound signal which has subjected to the
echo cancelling process, the sudden sound consisting of a
characteristic sound in which a sound generation time is shorter
than a reference threshold, and, when the sudden sound is detected,
the masking sound signal producing unit produces the masking sound
signal having a level corresponding to the amplitude level of the
picked-up sound signal which has subjected to the echo cancelling
process, at a timing outside a period including the sudden
sound.
To solve the problem, there is provided a sound masking method
which includes: a sound pick-up step of picking up a sound, and
producing a picked-up sound signal based on the sound; a masking
sound signal producing step of producing a masking sound signal
from the picked-up sound signal, the masking sound signal causing
the sound picked up in the sound pick-up step to be hardly hearable
by a third person; a masking sound outputting step of outputting a
masking sound based on the masking sound signal; and an echo
cancelling step of performing an echo cancelling process on the
picked-up sound signal by performing an adaptive filtering process
on the masking sound signal and by subtracting the filtered masking
sound signal, from the picked-up sound signal, and in the masking
sound signal producing step, a masking sound having a level
corresponding to an amplitude level of the picked-up sound signal
which has subjected to the echo cancelling process is produced.
Preferably, the sound masking method further includes a
transmission characteristic detecting step of acquiring
transmission characteristics to be used in the filtering process in
the echo cancelling step, and outputting frequency characteristics
of the transmission characteristics, and in the masking sound
signal producing step, the masking sound signal having a frequency
feature provided in the frequency characteristics of the
transmission characteristics is produced.
Preferably, in the masking sound signal producing step, an
adjustment content of the masking sound signal which is based on
the frequency characteristics of the transmission characteristics
is output, and, in the echo cancelling step, the adjustment content
is used in estimation of the transmission characteristics to be
used in the filtering process.
Preferably, the sound masking method further includes a
sudden-sound detecting step of detecting a sudden sound contained
in the picked-up sound signal which has subjected to the echo
cancelling process, the sudden sound consisting of a characteristic
sound in which a sound generation time is shorter than a reference
threshold, and, when the sudden sound is detected, the masking
sound signal producing step produces the masking sound signal
having a level corresponding to the amplitude level of the
picked-up sound signal which has subjected to the echo cancelling
process at a timing outside a period including the sudden
sound.
To solve the problem, there is provided a sound masking device
which includes: a receiving unit configured to receive a picked-up
sound signal; a masking sound signal producing unit configured to
produce a masking sound signal from the picked-up sound signal, the
masking sound signal causing a sound from which the picked-up sound
signal originates, to be hardly hearable by a third person; an
outputting unit configured to output the masking sound signal; and
an echo cancelling unit configured to perform an echo cancelling
process on the picked-up sound signal by performing an adaptive
filtering process on the masking sound signal and by subtracting
the filtered masking sound signal from the picked-up sound signal,
and the masking sound signal producing unit produces a masking
sound signal having a level corresponding to an amplitude level of
the picked-up sound signal which has subjected to the echo
cancelling process.
Effects of the Invention
According to the invention, a masking sound can be produced while
suppressing an influence of a sound other than a sound to be
masked. Therefore, it is possible to produce a masking sound which
is in accordance with a sound to be masked, and which is more
adequate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view showing an installation example of a sound masking
device of a first embodiment.
In FIGS. 2(a) and 2(b) are block diagrams showing the configuration
of the sound masking device of the first embodiment.
In FIGS. 3(a) and 3(b) are block diagrams showing the configuration
of a sound masking device of a second embodiment.
In FIGS. 4(a) and 4(b) are block diagrams showing the configuration
of a sound masking device of a third embodiment.
FIG. 5 shows an installation example of a sound masking device in
an environment which is partitioned by partitions into three
booths.
MODE FOR CARRYING OUT THE INVENTION
A sound masking device according to a first embodiment of the
invention will be described with reference to the figures. FIG. 1
is a view showing an installation example of the sound masking
device 1 of the embodiment. FIGS. 2(a) and 2(b) are block diagrams
showing the configuration of the sound masking device 1 of the
embodiment.
The sound masking device 1 of this embodiment is installed in an
environment such as shown in FIG. 1. FIG. 1 shows a case where
conversations performed across a counter in a pharmacy are masked,
as a specific example. Although only a microphone MIC and
loudspeaker SP of the sound masking device 1 are illustrated in
FIG. 1, other components of the sound masking device 1 may be
placed in a predetermined position of the room, another room, or
the like. The microphone MIC and the loudspeaker SP may be
integrated with or separated from the sound masking device 1.
Alternatively, only one of the microphone MIC and the loudspeaker
SP may be integrated with the sound masking device 1.
FIG. 2(a) is a block diagram showing the configuration of the sound
masking device 1 including the microphone MIC and the loudspeaker
SP. In the case where, as shown in FIG. 2(b), the microphone MIC
and the loudspeaker SP are disposed separately from a sound masking
device 1', a receiving section (receiving unit) which receives a
picked-up sound signal from the microphone MIC, and an outputting
section (outputting unit) which outputs a masking sound signal to
the loudspeaker SP are disposed in the sound masking device 1'.
A counter 910T is disposed in a room 900, and a clerk 901 such as a
pharmacist and a customer 902 have a conversation with each other
while facing each other across the counter 910T. A sound (voice
sound) generated by the clerk 901, and a sound (voice sound)
generated by the customer 902 are the sounds to be masked in the
embodiment. The microphone MIC (corresponding to "sound pick-up
unit" in the invention) which is a component of the sound masking
device 1 is disposed on the counter 910T.
Moreover, a store shelf and the like which are not shown are
disposed in the room 900, and third persons 903 exist in an area
where the store shelf and the like are disposed. The loudspeaker SP
(corresponding to "sound emitting unit" in the invention) is
disposed so as to emit a sound toward the area where the third
persons 903 exist. Based on the picked-up sound signal from the
microphone MIC, the sound masking device 1 emits a masking sound
from the loudspeaker SP so that the third persons 903 hardly
understand the content of a conversation between the clerk 901 and
the customer 902, and namely the sounds generated by the clerk 901
and the customer 902 are hardly heard by the third persons 903.
As shown in FIG. 2(a), the sound masking device 1 which produces a
masking sound includes the microphone MIC, the loudspeaker SP, a
masking sound signal producing section 11, and an echo cancelling
section 12.
The loudspeaker SP converts a masking sound signal Sm which is
produced by the process described later, to a masking sound, and
emits the masking sound.
The microphone MIC picks up the ambient sound containing sounds
(hereinafter, referred to as "specific person voice") generated by
the clerk 901 and the customer 902, and outputs a picked-up sound
signal Sr to the echo cancelling section 12. The picked-up sound
signal Sr contains also a feedback sound of the masking sound
emitted from the loudspeaker SP (hereinafter, referred to simply as
"feedback sound") in addition to the specific person voice.
The echo cancelling section 12 includes an adaptive filter 121 and
a postprocessor 122. The adaptive filter 121 estimates the
transmission characteristics of the feedback sound of the masking
sound based on an echo-cancelled signal Sre, and determines a
filter coefficient according to the estimated transmission
characteristics. The adaptive filter 121 performs a filter process
on a masking sound signal Sm by using the filter coefficient,
thereby producing a pseudo recurrent sound signal which corresponds
to the feedback sound of the masking sound. The postprocessor 122
subtracts the pseudo recurrent sound signal from the picked-up
sound signal Sr to produce the echo-cancelled signal Sre. The echo
cancelling process is consecutively made adaptive so that the
feedback sound component contained in the echo-cancelled signal Sre
becomes 0 (zero).
Therefore, the echo-cancelled signal Sre after adaption consists of
substantially only the specific person voice.
The masking sound signal producing section 11 produces the masking
sound signal Sm based on the echo-cancelled signal Sre. The
produced masking sound signal Sm is output to the loudspeaker SP,
and also to the adaptive filter 121 of the echo cancelling section
12.
Here, the masking sound signal producing section 11 produces the
masking sound signal Sm based on the time domain component and
component change of the echo-cancelled signal Sre, and the like.
Alternatively, the masking sound signal producing section 11 may
produce the masking sound signal Sm based on the frequency domain
component of the echo-cancelled signal Sre.
Specifically, in the case where the time domain component of the
echo-cancelled signal Sre is used, the masking sound signal
producing section 11 monitors the amplitude level of the input
echo-cancelled signal Sre, and produces the masking sound signal Sm
according to the amplitude level. In this case, the masking sound
signal Sm is configured by a disturbance sound and a background
sound. As the disturbance sound, for example, the sound of a crowd,
other arbitrary conversations, or the like is used. As the
background sound, for example, the sound of the nature such as a
mountain, a river, or the sea is used. The masking sound signal Sm
may be produced at an amplitude level at which, when the third
persons 903 hear the specific person voice and the masking sound
emitted from the loudspeaker SP, the specific person voice is
hardly hearable by a third person. Preferably, the amplitude level
of the masking sound signal Sm is set so that the masking sound
emitted from the loudspeaker SP is louder than the specific person
voice.
When the masking sound based on the masking sound signal Sm is
emitted, it is possible to make the specific person voice difficult
to be hearable by the third persons 903.
In the case where the configuration of the embodiment is employed,
even when the feedback sound of the masking sound is picked up by
the microphone MIC, the feedback sound components is suppressed by
the echo cancelling section 12. Therefore, the echo-cancelled
signal Sre which is configured by substantially only the specific
person voice is input to the masking sound signal producing section
11. Consequently, the masking sound signal producing section 11 can
produce the masking sound signal Sm which depends only on the
specific person voice, without being affected by the feedback sound
of the masking sound. Therefore, the amplitude level of the masking
sound signal Sm is not affected by the feedback sound, and the
amplitude level of the masking sound signal Sm can be set in
accordance with only the amplitude level of the specific person
voice. As a result, even when a masking sound which is higher in
level than required is not emitted, the specific person voice can
be masked while emitting a masking sound at an adequate volume.
Since the feedback sound is suppressed, the existence of the
specific person voice, i.e., the beginning and ending of speaking
of the specific person can be definitely distinguished. Therefore,
the masking sound signal Sm can be produced and emitted at an
adequate amplitude level, only in the case where the specific
person voice exists, in other words, during a period when the
specific person speaks. In the case where a masking sound is
steadily emitted, the masking sound signal Sm can be produced and
emitted at a high amplitude level, only during a period when the
specific person speaks.
As described above, when the configuration of the embodiment is
employed, the conversation of the specific person can be masked
practically and efficiently with respect to a third person.
Next, a sound masking device of a second embodiment will be
described with reference to the figures. FIGS. 3(a) and 3(b) are
block diagrams showing the configurations of the sound masking
devices 1A, 1A' of the embodiment.
The sound masking device 1A of the embodiment shown in FIG. 3(a)
has a configuration in which a transmission characteristic
detecting section 13 is added to the sound masking device 1 shown
in the first embodiment. The process of a masking sound signal
producing section 11A is different based on the additional
configuration. Hereinafter, therefore, only different portions will
be specifically described. Similarly with the sound masking device
1' shown in the first embodiment, the microphone MIC and the
loudspeaker SP may be disposed separately from the sound masking
devices 1A, 1A'.
The transmission characteristic detecting section 13 acquires the
transmission characteristics which are estimated by the adaptive
filter 121 of the echo cancelling section 12. The transmission
characteristic detecting section 13 analyzes the transmission
characteristics in the time and frequency domains. For example, the
transmission characteristic detecting section 13 analyzes a
frequency of long reverberation or the like in the environment
where the microphone MIC and the loudspeaker SP are disposed, from
the frequency feature of the transmission characteristics. The
transmission characteristic detecting section 13 outputs a result
of the analysis to the masking sound signal producing section
11A.
The masking sound signal producing section 11A produces a masking
sound signal Sma based on the echo-cancelled signal Sre and the
analysis result. In this case, for example, the masking sound
signal producing section 11A produces the masking sound signal Sma
so as to increase the amplitude level of a frequency of long
reverberation, based on the echo-cancelled signal Sre, i.e., the
specific person voice, and the analysis result as described
above.
According to the configuration, a masking sound of long
reverberation is emitted from the loudspeaker SP. Therefore, it is
further difficult for the third persons 903 to understand the
specific person voice. In the embodiment, the example in which a
frequency component of long reverberation is emphasized has been
described. Alternatively, another sound adjustment may be employed
as far as the masking sound signal Sma is produced based on the
acquired transmission characteristics so that it is further
difficult for the third persons 903 to understand the specific
person voice.
As shown in FIG. 3(B), the adjustment content (for example, a
frequency at which the amplitude level is increased) of the masking
sound may be output from a masking sound signal producing section
11A' to the adaptive filter 121. In the adaptive filter 121, the
input adjustment content is used in the estimation of the
transmission characteristics. For example, the adaptive filter 121
offsets the initial value in accordance with the adjustment content
of the masking sound.
When the adjustment content of the masking sound are given to the
adaptive filter 121 in this way, the adaptation of the adaptive
filter 121 can be rapidly converged. This enables an adequate
masking process according to the specific person voice to be
promptly started.
Next, a sound masking device of a third embodiment will be
described with reference to the figures. FIGS. 4(a) and 4(b) are
block diagrams showing the configuration of the sound masking
device 1B of the embodiment. FIG. 4(a) is a diagram showing the
whole configuration of the sound masking device 1B, and FIG. 4(b)
is a diagram showing the configuration of a sudden-sound detecting
section 14.
A sudden sound means a sound which is not correlated in amplitude
level and frequency characteristics with the disturbance and
background sounds constituting the above-described masking sound
signal Sm, and which is generated only a short time period (for
example, several seconds).
As shown in FIG. 4(a), the sound masking device 1B of the
embodiment has a configuration in which the sudden-sound detecting
section 14 is added to the sound masking device 1 shown in the
first embodiment. The process of a masking sound signal producing
section 11B is different based on the additional configuration.
Similarly with the sound masking device 1' shown in the first
embodiment, the microphone MIC and the loudspeaker SP may be
disposed separately from the sound masking device 1B.
As shown in FIG. 4(b), the sudden-sound detecting section 14
includes a sound signal monitoring section 141, a sound feature
analyzing section 142, and a sudden-sound information producing
section 143.
The sound signal monitoring section 141 buffers the echo-cancelled
signal Sre for a predetermined time length. The sound feature
analyzing section 142 analyzes the sound feature of the
echo-cancelled signal Sre which is sequentially buffered.
Specifically, the sound feature analyzing section 142 analyzes the
frequency spectrum, formants, and the like of the echo-cancelled
signal Sre, and outputs a result of the analysis to the
sudden-sound information producing section 143.
The sudden-sound information producing section 143 sequentially
stores results of the analysis, and sequentially detects the
similarity of the analysis results on the time axis. When a timing
at which the similarity is low is detected, the sudden-sound
information producing section 143 determines that a sudden sound is
generated at the timing, and outputs sudden-sound generation
information to the masking sound signal producing section 11B.
Upon reception of the sudden-sound generation information, without
using the echo-cancelled signal Sre at the timing, the masking
sound signal producing section 11B produces the masking sound
signal Sm in accordance with the amplitude level or the like which
is set at a predetermined timing that precedes the timing.
According to the configuration, even when the microphone MIC picks
up a sudden sound which is different from the specific person
voice, together with the specific person voice, an optimum masking
sound according to the specific person voice can be emitted without
being affected by the sudden sound.
In the sound masking device 1B shown in the embodiment, a sudden
sound is detected from the echo-cancelled signal Sre.
Alternatively, the picked-up sound signal Sr may be monitored, and
a sudden sound may be detected from a change of the sound feature
of the picked-up sound signal Sr.
According to the configuration, however, the echo-cancelled signal
Sre in which a feedback sound of the masking sound is suppressed by
the echo cancelling process is used. At a timing when a sudden
sound is picked up, therefore, the echo-cancelled signal Sre
contains only the specific person voice and the sudden sound. As
compared with the case where a feedback sound is contained,
consequently, sound features of the specific person voice and the
sudden sound can be more easily detected, and a sudden sound can be
more surely detected.
In the above-described embodiments, the case where one microphone
MIC and one loudspeaker SP are used has been exemplarily described.
The above-described configuration and process concept can be
applied also to the case where at least one of the microphone MIC
and the loudspeaker SP is disposed in a plural number.
For example, FIG. 5 shows an installation example of a sound
masking device in an environment in which three microphone MIC(A),
MIC(B), MIC(C), and two loudspeakers SP(FB), SP(FC) are placed, and
which is partitioned by partitions 910P into three booths. Even in
this case, the above-described configuration and process may be
applied to each combination of one microphone and one
loudspeaker.
Hereinafter, a summary of the invention will be described in
detail.
The invention relates to a sound masking device. The sound masking
device includes a sound pick-up unit, a masking sound signal
producing unit, a sound emitting unit, and an echo cancelling unit.
The sound pick-up unit picks up a sound, and produces a picked-up
sound signal based on the sound. The echo cancelling unit performs
an adaptive filtering process on a masking sound signal, and a
process of subtracting the masking sound signal which has subjected
to the filtering process, from the picked-up sound signal, thereby
performing an echo cancelling process on the picked-up sound
signal. The masking sound signal producing unit produces a masking
sound signal having a level corresponding to the amplitude level of
the picked-up sound signal which has subjected to the echo
cancelling process. The sound emitting unit emits a masking sound
based on the masking sound signal.
According to the configuration, even when the masking sound wraps
around and is then picked up by the sound pick-up unit, the
feedback sound is suppressed by the echo cancelling unit.
Therefore, a sound signal in which the feedback sound is suppressed
is input to the masking sound signal producing unit. Specifically,
for example, only the voice of the specific person to be masked is
input. This causes a masking sound to be produced based only on the
sound signal to be masked.
The sound masking device of the invention includes a transmission
characteristic detecting unit which acquires transmission
characteristics to be used in the filtering process in the echo
cancelling unit, and which outputs frequency characteristics of the
transmission characteristics. The masking sound signal producing
unit produces a masking sound signal having a frequency feature
provided in the frequency characteristics of the transmission
characteristics.
According to the configuration, a masking sound including also the
frequency characteristics of the transmission characteristics can
be produced. Therefore, it is possible to produce a masking sound
according to the picked-up sound environment. In the environment
(in a room) where the specific person exists, or the like, for
example, a masking sound or the like which more easily reverberates
can be produced.
The sound masking device of the invention includes a sudden-sound
detecting unit which detects a sudden sound contained in the
picked-up sound signal which has subjected to the echo cancelling
process, the sudden sound consisting of a characteristic sound in
which a sound generation time is shorter than a reference
threshold. When the sudden sound is detected, the masking sound
signal producing unit produces the masking sound signal having a
level corresponding to the amplitude level of the picked-up sound
signal which has subjected to the echo cancelling process, at a
timing when a sudden sound is not detected (timing outside a period
including the sudden sound).
According to the configuration, a masking sound including also a
result of the detection of a sudden sound can be produced.
Therefore, in the case where a sudden sound which is different from
the specific person voice to be masked is detected, for example,
the sudden sound is not used in production of a masking sound.
The above-described embodiments merely illustrate typical forms of
the invention, and the invention is not limited to the embodiments.
Namely, the invention may be performed with various modifications
without departing from the spirit of the invention.
The application is based on Japanese Patent Application (No.
2010-200468) filed Sep. 8, 2010 and Japanese Patent Application
(No. 2011-057384) filed Mar. 16, 2011, and the contents of which
are incorporated herein by reference.
INDUSTRIAL APPLICABILITY
It is possible to provide a sound masking device and sound masking
method which can produce a masking sound while suppressing an
influence of a sound other than a sound to be masked.
DESCRIPTION OF REFERENCE NUMERALS AND SIGNS
1, 1A, 1B sound masking device
11, 11A, 11A', 11B masking sound signal producing section
12 echo cancelling section
121 adaptive filter
122 postprocessor
13 transmission characteristic detecting section
14 sudden-sound detecting section
141 sound signal monitoring section
142 sound feature analyzing section
143 sudden-sound information producing section
MIC, MIC(A), MIC(B), MIC(C) microphone
SP, SP(FB), SP(FC) loudspeaker
900 room
901, 901A, 901B, 901C clerk
902, 902A, 902B, 902C customer
903 third person
910T counter
910P partition
* * * * *